Low spots and depressions in subfloor.
How to fix low spot under floating floor.
This should be a simple fix.
Be sure to use low expanding foam and i would also place a large heavy object on the floor above to be sure you do not push the flooring up with the foam.
It may require nothing more than simply sealing small gaps around your window panes with caulk.
It s not the depth of the depression that matters.
If a gap appears under the center of the level it indicates a low spot if the level rocks back and.
Mobile home windows also have a tendency to leak and may be allowing water to run down onto your floor where it seeps into the flooring and begins to create soft spots.
Place the level on different areas of the floor and notice if it lays flat in all spots.
You could do this from the bottom side in your case and drill a larger hole that the straw fits through.
Attach an air inflation needle as an extension onto a can of spray foam.
Some flooring such as solid wood or engineered wood can bridge small depressions.
Floor leveling compound is made for just such a thing.